This invention relates generally to fastening devices such as rivets, pins, threaded bolts and studs on which standards have been promulgated and which are used for locking, positioning, or entrapping plates or the like and more particularly to fastening devices as above enumerated which are self-locking, retractable, and reusable.
Fastening devices and/or fasteners when used herein are intended to mean rivets, pins, threaded bolts and studs on which standards for the clearance hole sizes for a given shank size have been promulgated either by commercial manufacturers and sellers of such fastening devices such as Acme Rivet Co., of Bristol, Conn.; SPS Technology Co., of Jenkinstown, Pa., and others or in the case of metric threaded fastening devices nationally by the Industrial Fastener Institute, of Cleveland, Ohio.
Since clearance hole size affects the available underhead bearing surface of area and hence the strength and performance of both the fastening device and the joint made with an associated member, plate, wall, and the like being locked, positioned or entrapped, "clearing hole", "sized clearing hole", "sized clearance hole" and the like expressions when used herein are intended to mean the said clearing hole standards so promulgated for fastening devices.
These definitions are best illustrated by reference to the following table taken from the above-mentioned sources.
______________________________________ CLEARANCE HOLE DIMENSIONS AND TOLERANCES FOR FASTENING DEVICES SUCH AS RIVETS, PINS, THREADED BOLTS AND STUDS WHERE SHANK "A" REPRESENTS THE DIAMETER OF THE BODY OF A GIVEN FASTENING DEVICE Recommended Clearance Hole Size Nominal Shank "A" Rivets Pins Blts & St'ds Size Max./Min. Max./Min. Max./Min. Max./Min. ______________________________________ 1/8"--.125 .123-.118 .128-.125 .127-.124 .136-.130 3/16"--.188 .186-.181 .196-.191 .191-.187 .209-.199 1/4"--.250 .248-.243 .265-.260 .253-.249 .286-.276 5/16--.313 .311-.306 .328-.323 .316-.312 .349-.339 3/8--.375 .373-.368 .390-.385 .378-.374 .441-.401 7/16--.438 .436-.431 .453-.448 .441-.437 .475-.465 1/2--.500 .496-.491 .516-.510 .504-.499 .536-.526 ______________________________________ (Clearance hole dimensions for components; NOT for mating parts i.e., threaded hole or nut)
There are of course known types of fastening devices in the prior art as is shown by U.S. Pat. Nos. 2,408,340 and 2,758,498 which are hollow shank fastening devices as distinguished from the solid shank fastening devices contemplated by the disclosure in the present application. In practice, these prior art fastening devices do not provide the relatively high degree of strength and compressive forces often required for industrial, commercial and even consumer used. This deficiency stems primarily from the structural limitations embodied in the design concepts of these prior art devices. Additionally, these prior art devices due to their complex structures are expensive to manufacture.
By modifying the configuration of the known commercially available fastening devices, the present invention provides improved fastening devices which are not only retractable and reusable but additionally provide a "self-locking" feature. This improved structure is accomplished without changing the character of the original fastening device and more importantly without requiring changes in the standards for the sized clearance hole required for a given type of solid shank fastening device.
The design characteristics of the improved fastening devices in accordance with the present invention lend themselves to very inexpensive mass production methods such as Cold-Forming, Progressive Die Stamping, and Robotic Assembly.
Further, the design of the improved fastening device in accordance with the present invention can be modified in various ways as is shown by the embodiments as hereinafter described in order to permit the use of these improved fastening devices for many applications. In particular, the improved fastening device is intended for use in mass production, high volume industries manufacturing products such as Automobiles, small and large, industrial, commercial and residential appliances, and the like types of products where it is desirable and beneficial to reduce costs and expenses of manufacturing these products and to avoid the secondary procedures of clinching the fastening devices or terminating the shanks of the particular fastening device by use of retaining rings, cotter pins, lock nuts, swaging, etc.